People, irrespective of their gender, have various modes of privacy. An introverted person could be seen as sad or as if they are hiding feelings. Similarly, sometimes extroverted people are seen as people who can never have problems.
We all have our unique problems. The challenge is to be patient with others in solving their problems while reciprocating the same gesture. If you are in a situation where you’d want her just to tell you what’s up, then take this ‘Is she trying to hide her feelings quiz’ and get an insight.